Rotary pump



Aug- 15, 1957 L.. T. CONDE ETAL 3,335,944

ROTARY PUMP Filed Sept. 14, 1964 LYALL T. CONDE CLINTON B. THulzaToN BY MW United States Patent O 3,335,944 ROTARY PUMP Lyall T. Conde, Sherrill, and Clinton B. Thurston, Oneida, N.Y., assignors to Conde Milking Machine Company, Inc., Sherrill, NX., a corporation oit New York Filed Sept. 14, 1964, Ser. No. 396,217 15 Claims. (Cl. 230-152) The following specification relates to dry air pumps and more particularly to pumps having a rotor with a plurality of vanes to produce a vacuum or air pressure.

Heretofore, it has been found that the manufacture of pumps, particularly for dry air applications, necessitated difficult and expensive manufacturing processes, difficult design problems, and great diiculty in repair and maintenance. These were all due, in part, to two factors: the need for close tolerances to be maintained within the pump body itself and on the rotor body, and the need for shimming devices to both prevent wear of the rotor and pum-p body, and to center the rotor within the pump body. If proper shimming was not provided for the rotor, the resultant wear led to sealing diculties and an accompanying loss in pumping efficiency. The shims themselves tended to be extremely fragile due to the extreme thinness required for proper sealing of the rotor within the pump, and thus led to frequent breakdowns and difiiculties in repair of broken pumps. Specialized tools had to be developed to repair such pumps, thus relegating maintenance to the factory or a specialist.

Thus, it is an object of the present invention to eliminate the need for shims within a dry air or oilless pump. Another object is a self-lubricating air pump. A further object is to provide a self-centering rotor within a dry air pump. A still further object is to provide a dry air pump that requires a minimum of specialized tools for its maintenance, Other objects will be apparent in the following specification and drawings wherein:

FIG. 1 is a front elevation of the pump body and installed rotor and vane assembly.

FIG. 2 is a front sectional elevation view of the rotor showing one means of attachment to the drive shaft of a motor.

FIG. 3 is a partial sectional side elevation of the pump shown attached to a motor power means.

FIG. 4 is an exterior side elevation View of the threepiece pump case detached.

FIG. 5 is a partial exterior view of the front cover plate depicting inlet and exit ports.

Our device comprises the use of a self-lubricating, oilless, relatively low friction rotor 1 containing vanes on a shaft 2, all of which are maintained within a three-piece pump body. The rotor is driven by a motor 4 or other suitable power means as may be desired.

More particularly, as seen in FIG. 2, the rotor 1 is shown attached to a shaft 2 by a flattened half round key 5, having a stud or projection welded or rigidly affixed to the opposite side flattened portion of the key 5. This stud or projection extends into a hole drilled through from the bottom of one of the vane slots to the center hole in the rotor. The matching at side of the key to the flat on the motor shaft with the extended stud or pin into the rotor body provides a driving means. The mounting of the rotor 1 on the shaft does not necessarily have to be rigid and preferably will allow some sliding along the drive shaft 2 to assure alignment within the pump body 7. An alternative mounting (not shown) might consist of rigidly aixing the rotor 1 to the drive shaft 2, said drive slidably mounted to the motor 4 such that the whole rotordrive shaft might align itself within the pump 8.

The relative location of the rotor-vane assembly within the pump body is most easily seen in FIG. 1. The interior 3,335,944 Patented Aug. 15, 1967 cavity 9 is of a somewhat larger diameter than the rotor 1 and has its center line offset from the center line of the drive shaft. The center lines remain parallel, however, the difference in diameters of the rotor and the pump body cavity, and the offset of center lines respectively, produces a crescent shaped cavity within the interior cavity 9. Equally spaced around the rotor body are vanes 3 (in the specific example, there lare four vanes) which are slidably held within radial slots 10 produced within the rotor body 1. As the rotor 1 moves in the direction shown in FIG. 1, the vanes 3 are forced by centrifugal action against the interior cylindrical wall that forms the interior cavity 9 to sweep the chamber and force air drawn from port 21 out the exit port 20. The rotor body 1 and vanes 3 are both made from an oilless self-lubricating relatively frictionless material such as polytetrauoroethylene, a polytetrauoroethylene-ber laminate, a graphite-asphalt mixture, a mixture of polytetrailuoroethylene and ground glass or other materials as may be suitable. Such materials have inherently low friction characteristics and require no lubrication in the present applications. The absence of abrasion and wear by this low friction, self-lubricating, oilless material eliminates the need for shim devices to maintain the rotor from rubbing on the end plates l2 or 13. The low friction material in the vanes 3 eliminates the need for lubrication within the pump body and substantially reduces the heat buildup of the pump.

The pump body 8 is formed by the center cavity portion 7 with end plates 12 and 13 fastened thereto by suitable fasteners such as machine screws communicating7 through holes 16, 17, and 18. O rings 22 and 23 contained within cavities 24 and 25 are used to seal the pump body 8 and prevent a loss in pumping efhciency. As seen in FIG. 1 and FIG. 5, the relative positions of the inlet port 21 and exit port 20 on the pump cavity chamber 7 can be seen by matching corresponding holes A and B of end plate 13, and the cavity chamber 7 respectively. -T he inlet port 21 and the exit port 20 are both located in the end plates rather than in the pump body 7 thus leaving the periphery of the body 7, on which the vanes 3 travel, smooth and free from interruption. These exit and inlet ports may be put in end plate 13 (as shown) or in both end plates 12 and 13 (not shown) or in end plate 12 (not shown). The relative position and size of the ports 20 and 21 are a matter of design only and are comm-only varied both dimensionally and in position to achieve maximum pumping efficiency. The maintenance of a desired position of the pump body 8 from the motor 4 is accomplished by the bolt assembly 28. In the present case shown in FIG. 3, the mounting of the pump to the motor is substantially rigid.

AS seen in FIG. 5, a wire screen or other suitable filter device 26 is shown over the inlet port 21 to prevent the entrance of dirt, dust, or other abrasive elements. The materials used for the pump body and end plates 12 and 13 in the present example are most advantageously and easily machined metal that will resist wear and dimensional change. Such metals may include steel, aluminum, magnesium or various alloys of each. Other metals as may be suitable are similarly included.

To achieve an oilless, self-lubricating air pump in whic-h lthe rotor would center itself within the pump chamber, various modifications are contemplated and are felt to fall within the scope of present invention. It is possible to make the end plates 12 and 13 from oilless self-lubricating materials similar to those already described for lthe rotor, and to make the .rotor from either met-al or a self-lubricating material. The only requirement is that wherever rubbing contact takes place between the rotor and the interior of the pump body, at least one of the members in contact shall leave its surface in contact made of an oilless, self-lubricating material. To

provide for centering of the .rotor-vane lassembly within; the pump body, various modifications in mounting the rotor to the driving shaft 2, in addition to those previously mentioned, are contemplated and have been successfully tried. In one instance, the drive shaft is disposed through both end plates 12 and 13 Aand is maintained in a desired position Within the pump body 7 by sealed bearing attached to said end plates. The rotor 1 may be mounted in this instan-ce to shaft 2 either fixedly or slidably as described previously, the single requirement being that the rotor 1 be able to center itself within the pump body.

The slots in the rotor may be produced either radially or tangentially toy the axis of said rotor. Either configuration is equally possible, the radial illustration shown for purposes of demonstration only.

xIt will be noted that various changes and modifications may be made to the instant structure and that the drawings and description herein contained are for the purpose of illustration only and are not to be construed as a limitation or definition of the elements of the invention, reference being had to the appended claims for the scope of the invention.

Having thus described our invention, what we claim as new Iand desire to secure by Letters Patent is as follows:

1. In a rotary pump, a casln-g having a cylindrical rotor chamber therein, a cylindrical rotor mounted in said chamber in eccentric relation thereto, a shaft affixed slidably and centrally within said rotor, said shaft driven by a motor power means, said rotor containing a plurality of slots along the outer periphery of said rotor, said rotor containing a plurality of vanes `slidable in said slots in a number equal to the number of slots in said rotor, said rotor of a self-lubricating relatively frictionless material, said rotor slidable along said shaft, end plates secured to said casing, said end plates having openings for penetration of said shaft, said end plates having suitable exit 'and inlet ports to interconnect the cylindrical rotor chamber with the atmosphere.

2. In a rotary pump as in claim 1, said rotor containing a plurality of vanes of a self-lubricating relatively frictionless material such :as polytetrafl-uoroethylene.

3. In a rotary pump as in claim 1, said rotor of a selflubricating relatively frictionless material such as polytetralluoroethylene.

4. In a rotary pump as in claim 1, said rotor of a selflubricating frictionless material comprising -a mixture of graphite and asphalt.

5. In a rotary pump as in claim 1, sai-d rotor of a selflubricating relatively frictionless material comprising a lamination of polytetrauoroethylene and inorganic fibers.

6. In a rotary pump as in claim 1, said rotor of a nonmetallic frictionless material comprising a laminate of polytetrauoroethylene and woven cloth.

7. In a rotary pump, a casing having a cylindrical rotor chamber therein, a cylindrical rotor mounted in said chamber in eccentric relation thereto, a shaft afxed centrally within said rotor, said rotor affixed rigidly to said shaft, said shaft in a slidable relationship to said cylindrical rotor chamber in a direction parallel to the axis of said cylindrical rotor chamber, said shaft driven by a motorpower means, said rotor containing a plurality of radial slots along the outer periphery of said rotor, said rotor containing a plurality of vanes slidable in said radial slots in a number equal to the number of slots in said rotor, said rotor of a nonmetallic frictionless nature, rend plates secured to said casing, said end plates having an opening for penetration of said shaft, said end plates having suitable exit and inlet ports to interconnect the cylindrical rotor chamber and the atmosphere.

8. In a rotary pump, as in claim 7, said rotor containing a plurality of vanes of a self-lubricating relatively frictionless material such as -polytetrafluoroethylene.

9. A rotary pump as in claim 1 wherein said slots are Y produced radially within said rotor.

10. A rotary pump as in claim 1 wherein said slots are produced tangentially within the rotor.

11. A rotary pump as in claim 6 wherein said slots are produced radially within said rotor.

12. A rotary pump as in claim 6 wherein said slots are produced tangentially within said rotor.

13. A rotary pump, a casing having a cylindrical rotor chamber therein, a cylindrical rotor mounted in said chamber in eccentric relation thereto, a shaft aii'xed centrally within said rotor, said shaft rigidly attached to said rotor, said shaft in a slidable relationship to said cylindrical rotor chamber in a direction parallel to the axis of said cylindrical rotor chamber, said shaft driven by a motor power means, said rotor containing a plurality of tengential slots along the outer periphery of said rotor, said rotor containing a plurality of vanes slidable in said tangential slots in a number equal to the number of slots in said rotor, said rotor of a self-lubricating frictionless nature, end plates secured to said casing, said end plates of a substantially self-lubricating frictionless nature, said end plates having suitable exit and inlet ports to interconnect said cylindrical rotor chamber and the atmosphere.

14. In a rotary pump as in claim 13, said rotor containing a plurality of vanes `of a self-lubricating relatively frictionless material such as polytetrafluoroethylene.

15. A rotary pump as in claim 11, wherein said slots in said rotor are produced radially to the axis of said rotor.

References Cited UNITED STATES PATENTS 2,616,615 11/1952 Scott 103-216 2,619,040 1l/1952 Maisch 103-126 2,818,025 12/1957 Hein 103-126 2,833,465 5/1958 Cable 103--216 2,880,676 4/1959 'Succop 103-126 2,925,786 2/1960 Hill 103-216 2,969,997V 1/1961 Runton et al. 103-114 3,016,019 l/l962 Rineer 103-136 3,187,993 6/1965 Rhodes 230-152 3,191,852 6/1965 Kaatz et al 230--152 3,191,853 6/1965 Kroger 230-152 FOREIGN PATENTS 122,069 3/1949 Australia.

ROBERT M. WALKER, Primary Examiner.

SAMUEL LEVINE, MARK NEWMAN, Examiners.

R. M. VARGO, W. J. GOODLIN, Assistant Examiners. 

1. IN A ROTARY PUMP, A CASING HAVING A CYLINDRICAL ROTOR CHAMBER THEREIN, A CYLINDRICAL ROTOR MOUNTED IN SAID CHAMBER IN ECCENTRIC RELATION THERETO, A SHAFT AFFIXED SLIDABLY AND CENTRALLY WITHIN SAID ROTOR, SAID SHAFT DRIVEN BY A MOTOR POWER MEANS, SAID ROTOR CONTAINING A PLURALITY OF SLOTS ALONG THE OUTER PERIPHERY OF SAID ROTOR, SAID ROTOR CONTAINING A PLURALITY OF VANES SLIDABLE IN SAID SLOTS IN A NUMBER EQUAL TO THE NUMBER OF SLOTS IN SAID ROTOR, SAID ROTOR OF A SELF-LUBRICATING RELATIVELY FRICTIONLESS MATERIAL, SAID ROTOR SLIDABLE ALONG SAID SHAFT, END PLATES SECURED TO SAID CASING, SAID END PLATES HAVING OPENINGS FOR PENETRATION OF SAID SHAFT, SAID END PLATES HAVING SUITABLE EXIT AND INLET PORTS TO INTERCONNECT THE CYLINDRICAL ROTOR CHAMBER WITH THE ATMOSPHERE. 